So, I've been breaking my head on the issue of how to best render clouds in UDK. Not just background clouds but the kind you could potentially move through. Using textures and sprites is easy and is the accepted way of doing it, but it has issues with shading and tends to look really bad when "inside". Volumetrics would be ideal but they tend to be very fuzzy and has poor performance. Using lots of smaller particles can look better shading wise but isn't much better in terms of perf. I'm kinda stumped on this one.